This invention relates generally to filtering devices, and more particularly, to methods and apparatus for use in capturing emboli within a blood vessel during endovascular surgical procedures.
Recent technology advances have been made in the area of cardiac surgery, including transcatheter valve replacement and repair procedures that may be performed without arresting the heart while systemic circulation is maintained. In some cardiac procedures, blood flow within portions of the heart, and aorta, must be interrupted, while other known procedures require cardiopulmonary bypass (CPB) with cardioplegia. However, technology advances, in areas such as echocardiography and flouroscopy, have enabled surgeons to visualize the cardiovascular system in more detail, and as a result, have enabled cardiac surgical procedures that do not require blood flow occlusion, or cardiopulmonary bypass. Because the patient's blood flow remains uninterrupted during such procedures, there are other inherent potential risks to the patient with such cardiovascular procedures. For example, the risk of stroke or neurologic deficit to the patient may be increased as a result of emboli, plaque, and/or thrombi being undesirably released into the blood stream. Clinical studies have shown that debris that is undesirably dislodged during manipulation of the heart and/or blood vessel may cause a stroke, other neurologic deficit, or infraction, depending upon where the debris travels within the patient's vascular system.
To reduce the likelihood of potential cerebral and/or other peripheral embolic events associated with such surgical procedures, several approaches have been developed to prevent emboli from traveling within the vasculature. For example, in at least some known procedures, a device may be inserted into the vessel in an attempt to deflect the emboli from one portion of the patient's heart, i.e., the carotid arteries, into a different area of the patient, i.e., the descending aorta. However, because such devices do not trap the emboli, a risk of embolisms in other areas of the patient's body remains and as such, such devices may provide only limited benefits.
Other embolic protection approaches include filtering devices that attempt to trap debris flowing through the vasculature. Positioning a filter in the vasculature during treatment can reduce the amount of embolic debris traveling in the bloodstream. Generally, such filters are inserted into the patient, with a containment catheter, in a collapsed state, and are sprung outwardly when released from the containment catheter and when positioned in a desired location within the patient's blood vessel. However, the use of such filters may be limited depending on the condition of the patient's vessels through which such filters are delivered to the treatment site. More specifically, because of their design and operation, some known filters may only be inserted within a patient via the femoral artery (transfemoral) or radial artery. Such devices are generally utilized for capturing embolic debris within saphenous vein graft or carotid stenting. However, because of patient limitations, such as weak or obstructed arteries, for example, some cardiac procedures may not be performed on a patient using a transfemoral approach. In addition, because of the fluidic pressure within the patient's blood vessel, at least some known filters may be difficult to secure in position within the vessel, may be difficult to accurately position within the patient, and/or may be used in only limited positions within the patient, such as within a portion of their aortic arch, for example.
Moreover, depending on the size of the mesh used in fabricating known filters, and depending on the amount of build-up within the patient, known filters may become quickly clogged, may create an unacceptably high pressure drop across the filter, and/or may obstruct the blood flow during the surgical procedure. Furthermore, many known filters are not sized to extend fully across the blood vessel, and as such only filter a portion of the blood downstream from the surgical treatment site, such that debris may either accumulate on external supports of the filter or flow past the filter.
After the surgical procedure is completed, known filters are generally collapsed and removed from the blood vessel. However, depending on the size of the filter and the amount of debris collected, as the filtering device is being collapsed for removal, it is possible for debris that has become stuck to the external supports of the filter to become dislodged and be carried away by the blood stream. Moreover, depending on the complexity of the filtering device, there may be a risk of trapped emboli escaping as the filter is collapsed within the blood vessel for removal from the patient. Accordingly, it would be desirable to provide an improved filtering device that does not obstruct blood flow while in use, that can be delivered to a desired location via a transapical delivery or through another vascular route, including a transfemoral passage, that may be easily positioned and centered within a desired location within a blood vessel, and that has a relatively simple design that provides the surgeon with a positive control of its use.